The robots, known as Spheres (Synchronised Position Hold, Engage, Reorient, Experimental satellites), currently have limited capabilities.

It is hoped the smartphones, powered by Google's Project Tango, will equip the robots with more functionality.

The robots have been described by experts as "incredibly clever".

When Nasa's robots first arrived at the International Space Station in 2006, they were only capable of precise movements using small jets of CO2, which propelled the devices forwards at around an inch per second.